Ultrasound imaging is a medical imaging technique for imaging organs and soft tissues in a human body. Ultrasound imaging uses real time, non-invasive high frequency sound waves to produce a two-dimensional (2D) image and/or a three-dimensional (3D) image. The sound waves transmitted into a region of interest are reflected and/or absorbed with each layer of tissue that is passed. Some structures allow the sound waves to pass through them more easily than others. For example, a small amount of energy may be absorbed by watery fluid, such as in an effusion or a cyst. Accordingly, regions lying behind the watery fluid may receive more of the ultrasonic signals than the processor of the ultrasound system expects for that depth, providing a uniformly brighter appearance. As another example, regions lying behind bone, such as the spine or ribs, may absorb and/or reflect more ultrasonic signals, leaving a dark acoustic shadow behind the structure.
FIG. 1 illustrates an exemplary fetal ultrasound image 10 as known in the art. Referring to FIG. 1, the fetal ultrasound image 10 may include acoustic shadow artifacts 12 from bones, such as the spine or ribs. In fetal ultrasound, for example, the visibility of structures may depend on the fetal position. Examining structures, such as the fetal heart, may be difficult due to acoustic shadow artifacts 12 created by the ribs and/or spine. In practice, an ultrasound operator may attempt to alter the angle in which the ultrasound probe touches the skin of the patient. Additionally and/or alternatively, a change of angle may be achieved via beam steering. Spatial compounding typically employs beam steering to transmit/receive ultrasound beams at multiple distinct beam angles which insonify a common region, from which multiple images are formed. The individual images may be detected, resampled onto a common grid, and combined in order to produce better image quality. One of the image quality attributes improved by spatial compounding is reduced shadowing artifacts. Although spatial compounding may help reduce shadow artifacts, acoustic shadows may still be present and/or otherwise detectable in ultrasound images acquired with spatial compounding.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present disclosure as set forth in the remainder of the present application with reference to the drawings.